Thousands of NHS patients are being discharged from hospitals every year in the middle of the night despite bosses ordering a crackdown on the practice, a Sky News investigation has found.

The number of patients leaving hospital in England between 11pm and 6am has actually risen in the last two years, new figures show.

In almost half of cases, the proportion of patients discharged overnight has increased.

In April 2012 NHS England medical director Professor Sir Bruce Keogh called on hospitals to cut down on overnight discharges following a series of cases where vulnerable patients had been left to make their own way home.

Image Caption:Dr Mike Smith has said the practice is driven by the need for beds

The NHS was accused of discharging patients overnight to try to free up beds.

However, figures obtained by Sky News following Freedom of Information (FOI) requests show that since Sir Bruce's intervention the practice is still widespread and in many cases rising.

According to the figures more than 300,000 patients have been discharged late at night since 2012 - an average of around 400 a night. Tens of thousands of those patients were over 75.

As only 72 of England's 160 NHS trusts were able to provide full figures for the last three years, the true number is certain to be far higher.

Dr Mike Smith, chair of the Patients Association, said: "They have got people in A&E chomping at the bit, lying in corridors, they have got to be admitted and they have no beds.

"It's for the convenience of staff and the person they are admitting but at the gross detriment to the person they are chucking out."

Experts say that patients often end up in care homes in the middle of the night.

Nadra Ahmed, chair of the National Care Association, said: "They are going back without any relevant information about how their care might have changed, what the diagnosis might have been, their paperwork is not following because people are off duty and often without the relevant medication they need for the following day or even through the night."

Patient Michael Atkinson told Sky News that in March 2013 he was discharged from the Royal Bolton Hospital A&E at 3am, despite being in a confused state.

He was found by police an hour later wandering on a cricket pitch almost a mile away.

He said: "I did not know who I was, where I was. I did not know where I was going. I was just wandering basically. I was in pain."

His wife Helen said: "He could have died. He was blue with cold. Something must be done to stop this happening. You are in hospital for a reason - to be looked after."

The hospital said that Mr Atkinson had left before transport could be arranged for him but said that staff had tried to learn lessons from the incident.

Sky News asked 160 NHS trusts in England how many patients had been discharged between 11pm and 6am in the past three years.

Video:Patient In Wales Discharged At 2am

Of those, 72 trusts provided figures for all three years. In 41 cases, the number of patients discharged overnight increased.

In 31 cases the proportion of patients discharged between 11pm and 6am increased. In three trusts it remained the same.

Of the 72 trusts that replied, 152,472 patients were discharged between 11pm and 6am in 2011/12, rising to 152,479 in 2013/14.

The figures also reveal that 20,152 were aged over 75 in 2011/12; 19,728 in 2012/13 and 18,548 in 2013/14.

The proportion of patients discharged overnight remained the same at 2.41%.

Some 25 trusts said they did not collect the data or that it would take too much time to find it and the remaining hospitals did not reply to the FOI request.

A spokesperson for NHS England said: "Discharging patients at night without appropriate support is unacceptable, particularly if a patient is vulnerable.

"Where a patient wishes to leave late at night or early in the morning, it should be accommodated only where it is safe and clinically appropriate and with the support of family, friends or carers.

"The decision to do this should always be based on what is best for the patient."

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